Safety device for blasting charges employed in mining and similar work



March 7, 1933. Wy VORTMANN 1,900,624

SAFETY DEVICE FOR BLASTING CHARGES EMPLOYED IN MINING AND SIMILAR WORKFiled Jan. 16, 1951 7 7f4 A i Bf 7mm/MM Patented Mar. 7, 12933 STAT'WALTER VOORTMAN'N, OF DORTMUND, GERMANY DEVICE FOB BLASTING CHARGESEMPLOYED IN MINING AND SIMILAR- WORK Application led January 16, 1931,Serial No. 509,247, and in Germany March 5, 1930.

This invention relates to a protective device for the blasting chargesthat are usual in mining and similar operations. It is y known to mountupon a blasting charge located in a bore hole, before tamping orstemming it, a plug that receives a pulling member, for the purpose ofenabling the blasting cap to be pulled out again in the event of failureof the explosion, after the tamping that closes the bore hole,consisting of moist clay or the like,u has been removed.

The object of the present invention is to provide a protective devicefor the blasting charges that are usual in mining and similar 5 oerations, characterized by the feature that t e plug, made of anincombustible material, impregnated wood for example, or anincombustible articial material, is provided with two longitudinalbores, for the ignition wires and for the pulling member respectively,and

has on the outside axially arranged and prefv erably dovetail-shapednotches for the reception of supporting members for a partial charge. 4

According toy a further feature ofthe invention the bore in the plug forthe pulling member is located centrally, and has at the inner end aconical expansion.

According to another feature of the invention the pulling memberconsists of an incombustible string or wire, which is held in the boreof the plu by a knot and preferably has a coloured mar 'ng.

invention the margins of the recesses in the plug for the supportingmembers are somewhat convergent towards one end, and the supportingmembers, which consist of incom- 40 bustible material, such as presspahnfor example, are provided with transverse holes at their ends.

By locating the pulling member exactly in alinement with the axis of thebore hole for the blasting charge, and firmly connecting a partialcharge with the plug by means of the supporting members, a reliableguidance y is established in the bore hole when inserting andwithdrawing the plug. In consequence v of the coloured marking of the.string it can According to yet a further feature of thel at any time beascertained how deep the plug is in the hole.

The invention is illustrated by way of example in the accompanyingdrawing, in

which Figure 1 shows a back view of the plug according to the invention.

\ Figure 2 a side view of the plug.

Figure 3 a side view of a plug with supporting members inserted and apartial charge fitted in, a

Figure 4 a side view of a supporting member, and

Figure 5 a blasting charge inserted in the e5 bore hole, on a smallerscale.

A cylindrical plug 1, illustrated in the drawing, preferably consists ofan incombustible material, for instance impregnated wood or anarticiflal material. The plug has in an axial direction a centralcylindrical bore 2 for the reception of a pulling member, not shown, anincombustible string or wire a for example. The bore 2 is conicallyflared towards the inner end of the plug, and in this conical widening 3is placed a knot on the pulling member, which prevents the string frombeing dragged out of the plug. Parallel to the bore 2 is provided asecond bore 4, through which ignition wires c, c for the blasting cap d.In the cylindrical surface of the plug are cut dovetail-shaped grooves 5and 6 parallel to the axis, which taper t0- wards the inside of theplug, as shown in Figure 2. Into the dovetail-shaped groves are insertedfrom the outside supporting memo bers 7 and 8, which likewise consist ofan incombustible material, such as presspahn. The shape of thesesupporting members is externally adapted to the periphery of the e plug.The supporting members 7 and 8 are 90 long bars, which are providedinthe neighbourhood of their ends with transverse holes 9 and 10respectively. Owing to the fact that the grooves 5 and 6 taper inwardsto some extent, the supporting members are firmly connected with theplug. j

The supporting mem ers 7 and 8 serve to hold a partial charge e insertedbetween them`I The ignition wires are passed y through the bores 4, andthe inner end of the partial charge is held by a string f ofincombustible material, which passes through the holes 9 and l0.

If no partial charge is desired between the bars they may be omitted,and the ignition wires may be passed through the laterally providedgrooves. The plug may also Ibe directly connected with the fuse, and theignition Wires are then so strong that they serve as a pulling member.

When inserting the partial charge connected with the plug, the whole isintroduced so far into the bore hole that the inner ends of thesupporting members come into contact with the preceding partial charge,as shown in Figure. The string, not shown, projecting from the outer endof the plug, and preferably having a colored marking, every Centimetresfor instance, indicates how deep the plug is in the bore hole.

The free end of the bore hole is closedin the usual manner, after theinsertion of the i plug, by the so-called tamping or stemming g or moistclay or the like. The string or the pulling member then projects out, asdo also the ignition wires.

If a miss-fire occurs, the tamping is blown out of the bore hole .bycompressed air by means of a blast pipe having an internal `diameter ofabout l() millmetres, and by exerting a pull on the string or wire a oron the ignition wires, the plug can be drawn out, together with thepartial charge (if any) connected with it. In Figure 5 three partialcharges are shown, inserted in one bore hole.

What I claim is 1. A safety device for blasting charges employed inmining and similar operations, consisting in the combination of acylindrical plug of incombustible material provided with a centralpassage, and a pulling member anchored axially of the passage in theplug, the pulling member being marked at definite distances.

2. A safety device for blasting charges employed in mining and similaroperations, consisting in the combination of a cylindrical plug ofincombustible material provided with a central passage, and a pullingmember anchored axially of the passage in the plug,y

ignition wires, the plug being formed with a second passage, parallel tothe said central passage, for the ignition Wires.

3. A safety device for blasting charges employed in mining and similaroperations, consisting in the combination of a cylindrical plug ofincombustible material and a pulling member attached centrally to theplug, ignition wires, the plug being formed with a central passage forthe pulling member, and with a second passage, parallel to the saidcentral passage, for the ignition wires, and with dovetail-shaped slotsin its cylindrical surface, supporting members engaging in thevLacasse-st said slots, and a partial charge held between the supportingmembers.

4. A safety device for blasting charges employed in mining and similaroperations, consistin in the combination of a cylindrical plug ofmcombustible material, supporting members connected with the plug, astring holding the supporting members together, a partial charge held bythe supporting members, and a pulling member attached centrally to theplug.

5. A safety device for blasting charges employed in mining and similaroperations, consisting in the combination of a cylindrical plug ofincombustible material, supporting members connected with the plug, a.string holding the supporting members .together, a partial charge heldby the supporting members, and a pulling member attached centrally tothe plug, the pulling member being marked at definite distances.

6. A safety device for blasting charges employed in mining and similaroperations, consisting in the combination of a cylindrical plug ofincombustible material, and a pulling member attached centrally to theplug, the plug being formed with a central passage for the pullingmember, supporting members connected with the plug, a string holding thesupporting members together, a partial charge he d by the supportingmembers, a blasting cap, and ignition wires for the electrical ignitionof the blasting cap.

In testimony whereof I have signed my name to this specification.

WALTER VOORTMANN.

